The key performance indicators of thermal energy storage (TES) units are the effective storage capacity and discharging rate. As it happened in building cooling applications, a latent heat thermal energy storage (LHTES) unit, which is a TES unit using phase-change-materials (PCM), when not properly designed, could have an effective storage capacity significantly lower than that of a stratified-water-storage (SWS) tank. This study experimentally demonstrates how the effective storage capacity and discharging rate of PCM-based TES units can be improved by enhancing heat transfer in PCM. To do this, four basic components of shell-and-tube LHTES units were filled with four different PCM composites, respectively, and tested under both laminar and turbulent flow conditions (Re: 500–14,500). The four selected PCM composites were composed of pentadecane and expanded graphite (EG), and achieved effective thermal conductivities (k_eff) of 0.21 W/(m·K), 1 W/(m·K), 8.6 W/(m·K) and 20 W/(m·K)), respectively. It was found that the test unit using pentadecane-EG composite with k_eff = 8.6 W/(m·K) can have an effective storage capacity twice that of an ideal SWS tank operating under Re = 4300 for the radiant cooling application condition. It has long been known that enhancing heat transfer in PCM could improve the performance of PCM based TES units. However, this is the first experimental confirmation that a PCM based TES unit can achieve an effective storage capacity higher than that of an ideal SWS tank; and the discharging rate of a PCM based TES unit could be improved under a realistic, practical operating condition.

热能存储（TES）单元的关键性能指标是有效存储容量和放电率。正如在建筑制冷应用中发生的那样，潜热热能存储（LHTES）单元是使用相变材料（PCM）的TES单元，如果设计不当，其有效存储容量可能会大大低于分层储水（SWS）储水箱。这项研究实验证明了如何通过增强PCM中的热传递来提高基于PCM的TES单元的有效存储容量和放电率。为此，在管壳式LHTES装置的四个基本组件中分别填充了四种不同的PCM复合材料，并在层流和湍流条件下进行了测试（Re：500–14,500）。k _eff）分别为0.21 W /（m·K），1 W /（m·K），8.6 W /（m·K）和20 W /（m·K））。结果发现， 对于辐射冷却应用条件，使用k _eff = 8.6 W /（m·K）的十五烷-EG复合材料的测试装置的有效存储容量是理想的SWS储罐的有效存储容量的两倍，该储罐在Re = 4300下运行。早就知道，增强PCM中的传热可以改善基于PCM的TES单元的性能。但是，这是第一个实验证明，基于PCM的TES单元可以实现比理想的SWS储罐更高的有效存储容量；在实际可行的工作条件下，可以提高基于PCM的TES单元的放电率。